Microbiology of fruit in relation to certain fruit products

Abstract

116arsenic rcniovcd froiii thc spciss nre prcsent ns sulphides in the nlknlinc iiintte, and licnce dissolvc with ease. .Kcncc tlic rilknliiic innttc is simply ground nnrl transfcrrcd to nn iron tnuk of In most otlicr briiiichcs of precioiis iiictal vmclting, grcnt siiiiplicity csistv bccnusc of tlic high spccific griivity of tlic vnliiidh coustitntcnts ciisiiring t.licir sinking to tlic bottom of 1111 rnoltcn niiisscs. Tlic reiison why licrivy ~nctuls, such ns iridiuin, osiiiiuin, rliodiuni, ;uid rutlicniuni cun Lc skiuinicil off froin thc surfncc of lcntl is thnt tlicir rcspcctivc nrscniclcs nll posscss low spccific griivitics, bccnuse niucli iirsciiic is conibiiied.lt'liis inforinrrtion conld bc gleiincd from cnrly clicniiciil dictionnrics diiting back to iiiorc tlirin 11 ccntiiry ago, but priioticnl iipplicntion wiis not iii:iilc until 11'1 lciinin iised i t for gololclsniith's sweepings some 60 yc;irs ago. In n siiiiilnr ~nnnner, instciid of gold sinking t o the bottom of the inoltcn uinss when tlic spciss is treatcd with the nlkalinc fusion, it is converted to tlic coiiipnrntivcly light siilpliidc, unrl thus is rcniovcd in tlic top mattc.Tlrc rcpcutcd siilpliurizing rctliicctl tlic wliitc-inctal to II coriccntrntctl spciss rcImscntec1 by it fcw hundredweights containing ahout 4 oilnets of gold pcr cwt. Tbo :ilhlinc niuttc wliicli aiiiorilits to inii1iy tous in \wight, is rccluccd to nbout two-thirds of its \wight by subseqiicntly wasliiug with hot water. This rcdiiction is c!ntircly clcpcu~lcnt upon tiic rnt,io of &in, antiniony, and ;irscnic, to tlic insolublc bnsc nictnl s~~lpliidcs, iis tlic sodiutn sulphidc ruiiiuins solublc. l'hc proccss rcvcnls tlliit gold ciin bc rcnio\~ed froiii wliitc-mctnl or siiciss nlniost in its cntirety by npplying siiitnblo sulpliiirieiug.As with otlicr sulpliides, tlic filtration prcscnts sonic sniiill practicnl difliciilticu, unlcss n good typo of vncuiini filter is cmpioycd. 'l!lic bliick prccipitiitc which cousisb of gold sulphitlc, nntl snlpliidcs of thc otlicr biisc metnls, is c!asily dcnlt with by chilrgi1Ig on to ii siiiclting furnnce whcrc tho rcgulnr work of tlciiling with prccioiis nictnl " swccp " nnd residues is curried oet. Gold siilphide rcudilg piirts nitli its sulphrtr to coppcr, iron, nrirl other biuc iiictnls in niost smclting trcut.mcnts, iind i t is rcgiirtlctl as ~1 good siilpliiirizing ngcnt.A tenipcriiterc bclow 300" C. sufficcs to tlcconiposc gold siilpIiitlc into gold niid siilpbnr, nnd liciicc in gcucral smclting i t is not f o l d in tlic condition of sidphide. Sulpliur rcfiuing of gold dntcs bnclr to tlic clewnth ccntury \rhcn 11 description of the mctlrod wis witton Iiy Tlicopliilos, hiit tlic siilpiiurizing of spcias niore rc1:itctl to nickel nictiillurgy in eiirly yciirs, :iiitl in tlic foregoing iiistiincc t,lic sulphiir is usyd to collcct tlic gold. 'J'lic iniportniicc of tlic dlcct of thc originnl niicrobiologicd popiilntion of rnw fruit nintcrinl 011 tlic ultinintc product wries to R consiilcrnblc cstcnt nnd is lirrgcly ulfcctcid by t,lic ...

The Ecology of the Acetic Acid Bacteria with Particular Reference to Cider Manufacture

“…Barker (1922) stated that 'various kinds of bacteria are (also) to be found on the surface of the ripe apple, especially certain of the acetic forms'. Krehan (1930) found a strain which he named B. acetigenoideum on apples, and Charley (1939) recorded that B. xylinum had been noted on apple blossoms and remained throughout fruit development and cider production. Marshall & Walkley (1951) tried to correlate microbiological principles with apple juice production and carried out a quantitative survey of the organisms present on and in apples at different times of the year.…”

CONTROL of ENZYMATIC BROWNING IN RAW FRUIT JUICE BY FILTRATION and CENTRIFUGATION

“…Although the ability of such procedures to remove preformed pigments resulting from enzymatic browning is recognized (Kilara and Van Buren 1989), their ability to prevent browning apparently has been overlooked. The cold sterilization of fruit juices by filtration was first investigated and used in Europe more than 50 years ago (Charley 1939; Smock and Neubert 1950;Borgstrom 1954). Juices prepared by this process retain the characteristic flavor of the fresh fruit and are free of cooked taste but may be unstable due to the presence of active enzymes (Borgstrom 1954).…”